Patent Literature 1 shown below discloses a planar waveguide laser apparatus comprising a core made from a laser medium, and reflective coatings formed on opposite two side surfaces of the core out of four side surfaces of the core.
In this planar waveguide laser apparatus, laser light incident into the core propagates in a zig-zag manner while being repeatedly reflected between the two reflective coatings, so that the laser light is amplified.
Patent Literature 1 shown below further discloses a planar waveguide laser apparatus in which an angle of inclination is provided between two opposite side surfaces on which a reflective coating is formed.
In this planar waveguide laser apparatus, laser light incident from an incidence portion for the laser light propagates within a core in a zig-zag manner and is reflected, and the laser light that is reflected propagates backward within the core in a zig-zag manner, whereby the laser light is emitted from the same position as the incidence portion.
In the planar waveguide laser apparatus disclosed in Patent Literature 1 shown below, because the length of the propagation path of the laser light within the core of laser medium can be lengthened, high-gain amplification of the laser light can be carried out.
In addition, because in the planar waveguide laser apparatus, pump light is incident from a side surface of the core of laser medium, the overlap between the laser light and the pump light can be increased, and the laser light can be amplified efficiently.